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(No Model.)

Si Zl DE PEREA-NTL 2 Sheets-Sheet 1l CONDUCTOR TON CONVEYINGELECTRICITY.

Patented Aug. 20, 1889.

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(No Model.)

S. Z. DE FERRANTI. CONDUCTOR PON CONVEYING ELECTRICITY.

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UNITED STATES PATENT OEEICE.

SEBASTIAN ZIANI DE FERRANTI, OF IIAMPSTEAD, COUNTY OF MIDDLESEX,ENGLAND.

CONDUCTOR FOR CONVEYING ELECTRICITY.

SPECIFICATION forming part of Letters Patent No. 409,181, dated August20, 1889.

Application filed September 211, 1888. Serial No. 286,208. (No model.)Patented in England December 11,1885, No. 15,251; in

France December 9, 1886, No. 180,176; in Belgium Ianuary 8, 1887, No.75,875, and in Italy Ianuary 19, 1887, No. 21,119.

To all whom it may concern:

Be it known that I, SEBASTIAN ZIANI DE FERRANTI, electriciaan, subjectof the Queen oi' Great Britain, residing at 120 Fellows Roads,Hampstead, in the county of Middleser, England, have invented certainnew and useful Improvements in Conductors for Conveying Electric Energy,(forwhich I have obtained Letters Iatent in Great Britain dated December11, 1885, No. 15,251; in France dated December 9, 188G,No. 180,176; inItaly dated January 19, 1887, No. 21,119, and in Belgium dated January8, 1887, No. 7 5,875,) of which the following is a specification.

This invention has for its object improvements in conductors forconveying electric energy and is applicable more especially forconveying powerful alternating currents from dynamos of high potential.I employ concentric conductors consisting; of metal tubes separated byinsulating` material. The insulator I employ is paper saturated withozokerit or other solid para'fne.

The tube serving as the inner conductor should be of copper. It is madein convenient lengths, each, say, twenty feet, and on each lengthparai'iined paper is wound to a suitable thickness. The length thusprepared is then inserted into a corresponding length of the tubeintended to form the outer conductor, which also should be copper, andthe whole together is then. drawn through a con edie, by which the outertube is slightly re@ duced in size until it ni ps tightly upon theparaiiined paper lapped around the inner tube. The lengths so preparedare coupled together so that the electrical resistanceat the joint maybe no more than at any other point in the length of the conductor. Thisis done as follows: The ends of the inner conductors are reained out toa conical form and a copper cone is inserted be tween them. The outerconductors have right and left screwthreads formed upon them. They arescrewed into a corresponding tei-rule and so drawn together. Theinterior of the fer rule is then iilled with paraiiine and the joint iscomplete; or, in place of using a screw-fer rule, the ends of theconductors are drawn together by clamps within a ferrule or socketpiecemade with cavities, into which white metal in a melted state is thenpoured. The metal when it solidiies solders the socketpiece to the outerconductors and completes the joint.

W'here an expansion-joint is required, 1 make it in the followingmanner: I insert into the ends of the inner conductors copper cones,which are connected by flexible strands, and I connect the outerconductors by a socket piece, as above described. The socket-piece inthis case, however, is made of great length and is corrugated, so thatit can elongate sufficiently to allow the expansion and cont-ractionrequired.

To prevent an arc being formed from the inner to the outer conductor,screens of vnlcanite are inserted between the conductors or within thesocket-piece. The outer tube of each conductor is cut away for somedistance from the end and is replaced by a tube of vulcanite. This isloosely surrounded by another tube of vulcanite extending over the twoends, and outside this again are two other vulcanite tubes, and theseare attached to the inner tubes of vulcanite beyond the extremities ofthe intermediate tube. Thus the free path from conductor to conductor ismade sufii ciently long to avoid all risk of an arc being formed.

Among the advantages which t-hese arrangements present are thefollowing: First, the tubular or hollow conductors convey alternatingcurrents with more ei'iiciency than solid conductors of the same area ofsection; second, however high the tension such conductors are absolutelysate, for the inn er conductor is entirely incased by the outer, and theouter conductor, being everywhere uninsulated, is approximately of thesame potential as the earth; third, as no insulation is required, theconductors can be laid anywhere, and no special precautions arerequired.

In the annexed drawings, Figure 1 is a longitudinal section of theconcentric con ductors. Fig. 2 is a longitudinal section taken at a,joint. Fig. is a modification of this joint. Fig. 4t is a longitudinalsection, and

Fig. 5 is a transverse section of an expansionjoint. Fig. G shows fullsize a transverse section oi a large electric main.

IOO

a is the inner tubular conductor, of copper. b is the outer concentricconductor, preferably 0i the same metal. c is the insulating` materialbetween the two. This insulating material consists of paper. 'lhat onwhich newspapers are printed is suitable. The paper is dipped into hotparaffine, so as both to saturate it completely and to leave a thin filmon the surface. The coated paper is cut to lengths equal to the lengthof the conductor a., and it is then rolled tightly around the conductorto the proper thickness. The outer conductor Z) is passed on to thecovered inner conductor with a loose iit, and is thenv drawn down on toit, as already stated.

In, Fig. 2, d shows the copper cone inserted between the reamed-out endsof the inner con` ductor when making a joint. c shows the socket intovwhich the outer conductors Z) Z) are screwed, preferably with right andleft screwthreads, but in any case so as to bring the ends ot theconductors a c. into contact with the cone (Z. c is a hole in the socketclosed by a screw-plug. After screwing up the socket it is .filled upwith paraffine, and a plug is then screwed into the hole e.

In the modification shown by Fig. the socket-piece is not screwed on,but it is provided with cavities to receive melted metal. The tubes i)i) enter the socket-piece freely. The ends oi the conductor c are drawnup to the cone d by cramps, and then. hot whitemetalis poured into thesocket-piece byholes in the side. The socket-piece and the tubes Z)where the white-metal comes into contact with it should be tinned, sothat the whole may become securely soldered together.

In Figs. -i and .if f are hollow cones or plugs ot copper screwed intothe conductors u. c, and these are connected by flexible wire strands gg, soldered to them. The socketpiece consists of a copper tube 7L 7i,corrugated, as shown, and the rings 41' if', fitting its plain ends.These rings inclosc between them a cavity for white-metal, and when thisis poured in the tubes l) and 7L and the rings 'i it" become solderedtogether. 7c 1 are vulcanite tubes, which are applied around the end of:each conductor c over the paper insulation after the tube f) has beenshortened.

The tubes 7U' fit closely upon the paraffned paper. Z a looseintermediate tube of. vulcanite. mm are outer vnlcanitetubcs. lhey arethickened at one end and fit upon the tubes 71'/ where these also areslightly thickcned.

The ,joint between the tubes 7L'y and in is made goed with india-rubbervarnish.

I am aware that British Patent No. lt of 1375 suggests the use of atubular conductor surrounded by insulating material wrapped spirallywith a copper strip.

I am also aware that it common to cover insulated wires with a sheathot' lead, and that it has been proposed to lay such a cable in the earthor water and to use the s ixferior metal sheath as the return-conductor.

I claim as my inventionl. The combination ot' two concentric conductorsconsisting oit the interior metallic tube a, the exterior solid metallictube fi, and insulating material Vfilling thc'space bet-weon them.

2. The combination oi two concentric conductors consisting,respectively, of the interior metal tube cy and the exterior solid metaltube i) and the intervening solid insulating material c, consisting ofpaper saturated with para'ffi ne.

23. An electric cable or comiuctor composed et an uninsulated exteriorsolid metallic tube h, an interior metallic tube o, and insulatingmaterial iilling the space between them.

el. The joint consisting ot two pairs oil concentric conductors U. andh, the metallic cone between the ends ot' the interior conductors c, andthe socket-piece coupling the outer tubes or conductors i).

5. The joint consisting oI two pairs of concentric conductors a and l),the metallic conc d between the inner conductors, and the socket-piecec, soldered to the outer tubes or conductors i).

